Western Australia
Technical Meetings

The Western Australian Division of the AAS will be holding a technical meeting at 6:00pm on Thursday 2nd December. The speaker will be Jacqueline Giles from the School of Environmental Science, Murdoch University, who has been doing some fascinating work recording the underwater sounds in freshwater lakes. You will find a brief description of her talk below. The talk will be followed by pizza and refreshments. Non-members are also welcome.

The meeting will be held in the Physics seminar room at CURTIN University. This is room 147, Building 301. Check your street directory for a map of the campus or visit http://www.properties.curtin.edu.au/your_campus/maps/.

Park in carpark 18, which is just behind the bus station but only accessible from the campus ring-road (Brand Dve). Parking is free after 5pm. Follow the path westward past Building 311 and enter Building 301 through the door in its eastern end. This brings you in on Level 1 and the seminar room is at the far end of the corridor on the left hand side. If you are interested, could you just send Terry or Alec an email so we can get a handle on numbers.

For further information contact Alec Duncan on 9266 3569 (W) or a.duncan@cmst.curtin.edu.au

FRESHWATER MUSICIANS: THE ARIAS AND THE HALLELUJAH CHORUSES: The sound field in three clear-water wetland systems

Jacqueline Giles hilltoppine@hotmail.com
School of Environmental Science, Murdoch University, South St, Murdoch, WA 6150

A series of underwater, ambient sound recordings were made in three freshwater, clear-water systems –Blue Gum Lake, Glen Brook Dam and Lake Leschenaultia. These wetlands differed in terms of their location, buffers, nutrient enrichment, water depth and complexity within the habitat. The frequencies utilised by the invertebrate organisms ranged from 3kHz to 13.5 kHz. Blue Gum, the most enriched of the three wetlands with greatest diversity and abundance of invertebrates, had chorusing at dusk and midnight. Calls were mostly percussive but one complex call was heard, which was interesting because of its bird-like song quality.

For the first time, underwater vocalisations have been recorded for the Oblong Turtles (Chelodina oblonga), which are the long-necked turtles inhabiting these wetland systems. Underwater vocalisations have never been recorded for any freshwater turtles before. The Oblong Turtles use an extensive repertoire of percussive and complex sounds, ranging from 200 Hz up to around 2 kHz with sounds including ‘chirps’, ‘lion growls’, ‘squawks’ and ‘clicks’. Of special interest, was the recording of a 9 minute ‘song’ by a male turtle.